#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000001

int main(){
	
	int n;
	cin>>n;
	
	vector<vector<int>> E(n);
	rep(i,n-1){
		int p;
		cin>>p;
		p--;
		E[p].push_back(i+1);
	}
	
	int cnt = n-1;
	cnt -= E[0].size();
	
	cout<<mint(2).pow(cnt).val()<<endl;
	
	return 0;
}